This invention relates to aircraft de-icers and more particularly to an improved inflatable de-icer or boot adapted for attachment to the airfoil of an aircraft for use in retarding the accumulation of ice or to remove or break up ice accumulation.
Aircraft inflatable de-icers, pads or boots are made of resilient material such as rubber and attached to the leading edge of an airfoil and extend rearwardly therefrom. The de-icer has a series of inflatable passages or tubes which are distended by inflation pressure to break up ice accumulation which tends to form on the surface of the de-icer. The passages or tubes are deflated by releasing the pressure medium and drawing a vacuum thereon. The normal sequence of operation is a continuous cycling of the inflation and deflation process. An example of a de-icer in the art is presented in U.S. Pat. No. 4,779,823 PNEUMATIC DE-ICER, Ely et al. This de-icer incorporates a multitude of spanwise inflatable passages on either side of a leading edge that run parallel to the leading edge. A non-inflatable region overlies the leading edge. The inflatable passages to one side of the leading edge are cycled alternatively with the inflatable passages to the other side of the leading edge which generates a clamshell action that more effectively removes ice by cracking the ice accumulation along the leading edge. Another de-icer in the art is presented in U.S. Pat. No. 4,561,613 DEICER FOR AIRCRAFT, Weisend, Jr. This de-icer incorporates a multitude of chordwise inflatable passages that are parallel to the airstream that impinges upon the de-icer and passes around the airfoil. In general, chordwise tubes are less disruptive to the surrounding airstream that passes over the airfoil than spanwise tubes during inflation of the de-icer. Conversely, spanwise tubes remove ice much better than chordwise tubes on many airfoil geometries, particularly those geometries that have small leading edge radiuses.
Modern aircraft have flight surfaces that are sensitive to perturbations in the airstream that passes over the airfoil. Changes in an airfoil shape during inflation of a de-icer can cause undesirable changes in the aerodynamic characteristics of the airfoil. Therefore, a de-icer is desired that effectively removes ice without undesirably effecting aerodynamic characteristics.